Thread grinding machine



May 26, 1931. H. E. DURKEE THREAD GRINDING MACHINE Filed OCt. 14. 1929 2 Sheets-SheetY l f f ISM. Prh'HVdbD lllllllll Il INVENTOR gaa@ i `May 26, 1931. H. E. DURKEE 1,807,516

THREAD GRINDING MACHINE Filed oct. 14, 1929 2 sheets-sheet 2 INVENTOR M ATTORNEY Patented May 26, 1931 UNITED STATES PATENT OFFICE HENRY E. DU'RKEE, OF MANCHESTER, CONNECTICUT, ASSIGNOR TO PRATT & 'WHITNE COMPANY, OF NEW YORK, N. Y., A CORPORATION OF'NEW JERSEY l ,THREAD AGRINIDING MACHINE Application ,led October 14, 1929.

This invention relates to thread grinding machines and in particular to a mechanism permitting correct grinding operations to take place in both directions of rotation and travel of the work past the wheel.

Heretofore it has been usual to grind threaded work during rotation of the work in one direction only and while it is moving in one direction only past the wheelf At the end of a grinding operation in one direction the work and wheel are relatively separated, the work returned to its initial position and then again advancec1 into work engaging position for a second operation-in the same direction of rotation and travel.

A- primary object of the invention is to provide improved means whereby the back lash or lost motion betweeen the driving and driven connections of a thread grinding machine between the rotating and advancing mechanismfor the work may be adjusted during rotation of the work spindle and during normal operations of the machine so that grinding operations may take place in both directions of rotation and travel of the moving parts.

A feature of importance'or` theinvention is t0 provide a regulatable amount of lost motion between the work supporting and rotating spindle land its driving member, means being provided to adjust the amount of this lost motion by normally inoperative mechanism which may be operated at any time during operation of the machine. The total amount of lost motion between the driving means and the rotating means for the work may be varied so that it may be made equal to the lost motion between the driving means and the carriage supporting the work r0- tating spindle.

The object accomplished thereby and comprising a primary object ofthe invention is that reversal of .the driving member will cause reversal of rotation of a spindle and reversal of travel of av carriage simultaneously. y

With these and other objects in view, my invention consists in the features of construction and operation set forth in the following serial No. l399,618.

specilication and illustrated `in the accompaning drawings.

In the accompanying drawings annexed hereto and forming a part of this specification, I have shown my invention embodied in a thread gage grinding machine adapted to rotate and traverse a member to beI ground past a wheel fixed in position during the grinding operations, but it Will be under-A stood that the invention may be otherwise embodied and that the drawings are not to be construed asA dening or limiting the scope,

of the invention, the claims appended to this specification being relied upon for that purpose,

In the drawings: Figure l is a front elevation of a thread gage grinding machine, parts only of the construction being shown.

Fig. 2 is a longitudinal sectional View through the driving mechanism for the work supporting and rotating members.

' Fig. 3 is a detail view showing the means for regulating or varying the amount of lost motion between the main driving element and the work supporting and rotating spindle, and

Fig. 4 is a cross sectional view of the parts shown in Fig. 3 taken upon the line 4 4 thereof.

In the above mentioned drawings I have shown but one embodiment of the ln'ventionV understood, however, that changes and modiications may be made Within the scope of the appended claims without departing from the spirit of the invention.

In connection with thread grinding operations, it has been' the usual or standard practice to performthe grinding operationwhile the work is being rotated in one direction and being axially. advanced relative to the wheel in one directlony only. At the end of the grinding operation in` one direction the wheel and work are separated, returned to their initial positions and threading operations continued in the same manner.

In patent'to Schramm 1,634,386 granted July 5, 1927, means is shown and described whereby lost motion between the driving means for a work spindle and its rotating means may be widely adjusted. By this means it is possible to so adjust the machine, when being initially set up, to make the lost motion or back lash between the interconnected parts equal to an amount corresponding to the pitch or lead of the screw being ground. The mechanism therefore can be reversed at the end of each stroke of the work, as the work and the wheel will then properly engage the work during the reverse rotation and traverse movement of the work.

This construction, however, requires a special and manual operation to be performed upon normally rotating parts to effect any regulation of the4 amount of lost motion. The adjustment, therefore, cannot be varied for grinding operations upon differentpieces of work during the normal grinding operations of the machine.

The present invention, therefore, is to improve the construction shown in the Schramm patent to enable an operator to adjust the back lash or lost motion during operation of the machine, to permit grinding operations in reverse directions of rotation and relative axial movement of the wheel and work, regardless of the particular lead or pitch of the screw threads being ground.

Referring more in detail to the figures of the drawings, I provide a base 9 on which is slidably mounted a work supporting table 11. This table 11 may be reciprocated' by the means shown, in which a nut 12 fixed to the bed or base 9 is engaged by a screw 13 which has its end rotatably fastened within but held against axial movement within a part 10 depending from the slide or table 11. Rotation, therefore, of the screw 13 will move th-e supporting table 11, which may be reversed in the usual manner as by controller dogs controlling the reversal of the operating means such as shown in the patent to Schramm.

This screw 13 is adapted to be driven through appropriate gearing 14, the ratio of wlnch may be widely varied by substitution of different gears. The screw 13'is driven through these gear connections from a shaft 15 geared directly to a gear 16 on the main driving sleeve 17 directly adjacent and keyed to the main driving pulley 18. There inevitably will be a slight amount of lost motion between the driving sleeve 17 and the nut 12 engaged by the screw 13 so that, upon reversal of direction of the driving pulley 18 and its sleeve 17, movement of these driving elements through a definite angle will take place in the opposite direction before movement of the tablell. l

Adapted to be' driven from the driving sleeve 17 is the work supporting and rotating spindle 19 which is also suitably mounted upon the slide or supportingtable 11. This spindle 19 at one end has a face plate 20 and driving dog 21 construction or chuck adapted to directly engage one end of the gage or other work W being ground. The opposite end of the work piece is engaged within a center 22 mounted in a tailstock 23 of usual construction also on the supporting table 11. From .the above description it will be seen that rotation of the driving sleeve 17 and also the work spindle 19 will advance the work supporting table or slide 11, the rotation of the work and its axial Amovement being in any desired relation, determined by c means of the gearing 14. As the pulley 17 is reversed periodically during the normal operation of the machine the work spindle 19 and work WI will be rotated and moved axially first in one direction and then in the other.

Preferably positioned in rear of the work AW and suitably mounted for rotation by `means not shown in the present drawings is the grinding wheel 25, the periphery of which is formed to correspond to the work being ground. The head within which the wheel 25 is mounted is adjustable toward and from the axis of the work W to permit adjustment for different diameters of the wheels and work.

The driving connectionsbetween the driving sleeve 17 and its pulley 18 and the work supporting and rotating spindle 19 are shown clearly in longitudinal section in Fig. 2 and will now be referred to. this sleeve 17 which also carries the driving gear 16 for the table advancing or lead screw 13, is drivingly connected by means of a key 26 to a sleeve 27 recessed for a purpose presently to be described. This sleeve 27 fits within the sleeve 17 and within it passes a short shaft 28. This sleeve member 27 also is splined to the shaft 28 by means of a key 29 retained against axial movement within the sleeve 27 so that the shaft 28 may slide axially within this recessed sleeve 27. Also mounted Within the recessed portion of this sleeve 27 is a driving sleeve 30 shown in outline more clearly in Fig. 3. This driving sleeve 30 has an opening 31 of peculiar form extending diametrically through the sleeve 30 as shown in Fig. 3 so that a pin 32 drivingly held within the shaft 28 may have a considerable freedom of rotation relative to the sleeve 30. In positions of the shaft 28 more and more toward the left, as seen in Figs. 2 and 3, this angular freedom will become restricteduntil finally with the pin at the extreme left end of the opening within the sleeve practically no back lash or lost motion will be permitted between these two parts 30 and 28.

At the end of this mechanism adjacent the work spindle 19 the sleeve 30 is provided with large clutch teeth 33 which are in mesh with corresponding clutch teeth in a member It will be noted that 34 keyed directly to the work supporting and rotating spindle 19. Rotation, therefore, of the sleeve drives the work W, this movement being reversed as to direction of l rotation by reversing the rotation of the sleeve 30. With each reversal of'rotation of the driving pulley 18 and its sleeve 17 a "limited angular motlon of those parts must The table 11 will begin to m'ove in the opposite direction only when the lost motion between its driving connections lfrom the gear 16 to the nut 12 is taken up. By adjusting the position of the pin 32 axially within the opening 31thelost'motionbetween the driving gear 16 andthe spindle 19 can be made equal to that between the/driving gear 16 and the screw 13 for the table 11. With this adjustment made the work W will start its rotation in the opposite direction simultaneously with its reversal of lineal movement.

In order to vary the position of the shaft 28 during normal operation of the machine so that adjustments of lost motion may be made, the shaft 28 has on one end a flanged collar 35 secured in anypr'eferred means permanently in position upon this shaft -28 as by means of pins 36. The ianged portion of the collar 35 is angaged by a member 37 having surfaces engaging opposite sides of the flange-and held against rotationvby a stud 38 fitting within a longitudinal groove withinthis member. The shaft 28 is free to rotate Within the member 37, the member 35 also turning with the shaft 28. A hand wheel 39 at .the extreme left end of the machine supported for rotary movement but is prevented from moving axially by its mounting within a housing 41 enclosing the member 37.

This housing 41 is fixed to and forms a part of the head within which are mounted the driving connections for` the spindle 19. Rotation of this hand wheel 39 rotates a screw engaging screw threads within the member 37, so that lthe position of this member 38l and therefore of the axial position of the shaft 28 relative. to the sleeve 30 can be controlled.

What-I claim is: 1. A thread grinding machine comprising in combination, a base, an abrasive .wheel mounted thereon, a reciprocatory table, a work supporting and rotating spindle on said table, means to rotate said spindle, connec` tions between said .means and said table whereby said table is moved past said wheel in timed relation to the rotation of said spindle, and axially Ymovable means within said driving connections to vary the amount of lost motlon between said rotating means and said spindle.

2. thread grinding machine comprising in combination, a base, an abrasive wheel thereon, areciprocatory table, a work supporting and rotating spindle on said table, driving means for rotating said spindle and moving said table, connections between said driving means and said table, connections between said driving means and said spindle whereby said table is moved past said wheel in timed relation to the rotation of said spindle, and a manually rotatable member to vary the amount of lost motion in one of said connections during operation of the machine.

.3. A thread grindingv machine comprising in combination, a base, a table, a Work supporting and rotating spindle thereon, rotatI lng means for said spindle, a lost motion'con nection between said rotating means and said spindle, connections between said, means and said table whereby said ,table ismovable in any desired timed relation rotating to therotation of said spindle, and means.

to vary the 'amount of lost -motion between said rotating means and said spindle,

whereby reversal of said rotating me ns willl cause said spindle and table to beweversed precisely simultaneously.

4. A thread grinding machine comprising in combination, a base, an abrasive wheel mounted thereon, a reciprocatory table, a work supporting and rotating spindle on said table, means to rotate said spindle in timed 'relation to movements of said table, dr1v1ng means,'connec,t1ons therefrom to said v table, connections from said driving means to said spindle, and means to regulate the amount of lost motion' inone of said driving connections while said table and spindle are in operation whereby reversal of said driving means will cause simultaneous reversal of said spindle and table movements.

5. A thread grinding machine comprising in combination, a base, an abrasive wheel thereon, a reciprocatory table, a work supporting and rotating spindle thereon, means to rotate said spindle in timed relation to movements of said table, unitary driving means for said spindle and for said table,

changel gear connections therefrom to said table, connections from said driving means to rotate said spindle, and means to regulate the amount of lost motion in the connection from said. driving means to said spindle while said table and spindle are in operation.

6. A driving spindle comprising in combination, a sleeve,

means'to rotate said sleeve, a. second sleeve connection .for a rotating within said first sleeve, meansI connecting said sleeves for simultaneous rotation, a shaft splined to and axially movable within said second sleeve, a driven member within 5 said sleeve having an opening therein, a driving pin on said shaft and extending within said opening, means to axially adjust the axial position of said shaft relative to said driven member, and a` driving connection between said driven member and the spindle being driven.

7. A driving connection for a rotating spindle comprising in combination, a sleeve, means to rotate said sleeve, a second sleeve Within said first sleeve, means connecting said sleeves for simultaneous rotation, a shaft splined to and axially movable within said second sleeve, a driven member within said sleeve having an opening therein, a driving V pin on said shaft and extending within said opening, a driving connection between said driven member and the spindle being driven, and means to adjust the'axial position of said shaft during normal operation otsaid g5 parts. o 8. A driving connection for a rotating spindle comprising in combination, a sleeve, means to rotate said sleeve, a second sleeve within said first sleeve, means connecting 30 said sleeves for simultaneous rotation, a shaft splined to and axially movable within said second sleeve, a driven member within said sleeve having an elongated opening therein of variable width, a driving pin on said shaft a5 and extending within said opening so that it may engage one or the other side wall of said opening, means to adjust the axial position of said shaft relative to said driven member whereby said pin will be disposed in different 40 portions of said opening, and a positive driving connection between said driven member and the spindle being driven. f

In test1mony whereof, I hereto affix my signature.

HENRY E. DURKEE. 

